JP5482369B2 - Gas flow velocity measuring method and gas flow velocity measuring device - Google Patents

Description

  The present invention relates to a gas flow velocity measuring method and a gas flow velocity measuring apparatus for measuring the flow velocity of gas in a blast furnace at the top of a blast furnace.

  In a blast furnace, which is a steel production facility, raw materials such as iron ore, sintered stone, and coke are charged from the top of the furnace, and hot air is blown from the tuyeres provided in the lower part of the furnace to reduce the iron ore, sintered stone, and coke. Thus, pig iron is produced and pig iron and slag accumulated at the bottom of the furnace are sequentially discharged from the tap hole.

  At the top of the furnace, the movement of the turning chute is controlled, and a predetermined amount of charged raw material having a predetermined average particle diameter is laminated at a predetermined position. The upper surface of the raw material charged at this time is called the stock line, but as the reduction reaction proceeds in the lower part of the furnace, the stock line gradually decreases, and new raw material is charged from there. The operation of forming a stock line is repeated.

  The amount of coke as a reducing material necessary for producing 1 ton of pig iron in a blast furnace is called a coke ratio. In a blast furnace, this is an important factor, and if the coke ratio can be reduced, carbon dioxide emissions can be suppressed. In the blast furnace, the raw material charging method is used to reduce the coke ratio as much as possible, but further reduction of the coke ratio is required to suppress carbon dioxide emissions.

  In order to efficiently produce pig iron in a blast furnace, it is considered that the reduction reaction at the lower part of the furnace should be performed not only at the part near the center of the furnace but also at the peripheral part of the furnace (the part near the furnace wall). However, since the hot air blown from the tuyere is blown toward the center of the furnace, heat is released to the outside of the furnace near the furnace wall, and the reactivity is lower than that near the center of the furnace. It is thought that there is. Therefore, if the hot air blown from the tuyere can be adequately distributed in the raw material stacking condition after controlling the charging method of the charged material so that it can reach the surroundings sufficiently, It becomes possible to operate the blast furnace efficiently while suppressing the coke ratio. Conversely, an increase in the gas flow to the surrounding area is also an operational problem.

  Therefore, it is necessary to confirm that this charge distribution situation is appropriate. As a method for this, a method of measuring the flow rate of carbon monoxide and carbon dioxide blowing up from the bottom of the blast furnace is used. There is. In other words, the slow flow rate of the gas blown from the bottom of the furnace is thought to be a factor that hinders the flow of gas in the height direction of the blast furnace, and the coke functioning as a slit to facilitate the passage of gas. The charging method is not considered appropriate.

  Therefore, it is required to measure the gas flow velocity distribution in the stock line of the raw material. If this gas flow velocity distribution is known, it is possible to design the charge distribution so that the gas flow velocity flowing through the horizontal section of the blast furnace is the same overall, and that the charge distribution in the actual operation is appropriate. I can confirm. If a charge distribution having a uniform gas flow rate can be realized, the gas utilization rate can be improved, and a charge distribution with a reduced coke ratio can be performed. Here, the gas utilization rate is a ratio of carbon monoxide and carbon dioxide derived from coke, and a large value indicates that an efficient operation is performed.

  As a gas flow velocity measurement method, the technique described in Patent Document 1 is conventionally known. The laser Doppler velocimeter described here irradiates two different types of predetermined tracer gas with laser light, detects the absorption spectrum (peak value at which absorption occurs) of the laser light by each tracer gas, The gas flow rate of the tracer gas is obtained from the Doppler shift amount corresponding to the gas flow rate of the absorption spectrum. Further, the flow rate of the exhaust gas of the automobile is obtained by weighted averaging of the gas flow rates of the respective gases using the spectral intensities varying with the respective gas concentrations.

  As a method for measuring the gas flow velocity at the top of the blast furnace, for example, techniques described in Patent Document 2 and Patent Document 3 are known. In Patent Document 2, the inside of the furnace is imaged by a camera, the image is analyzed to extract the outline of the gas flow, the amount of change in the extracted gas flow outline position within a predetermined time is obtained, and the gas inside the blast furnace is obtained. A flow rate is obtained.

  In addition, Patent Document 3 discloses a microwave radar that transmits a fixed frequency radar attached to the tip of a lance provided with a control device that can be driven in the furnace radial direction and can be stopped at a measurement point in the furnace. The waves reflected from the furnace charge or floating dust are received by multiple receiving antennas installed on the lance, and the Doppler effect of the dust obtained from the gas blown from the bottom of the furnace is observed and the gas It is a technique for obtaining a flow rate.

JP 2008-170394 A Japanese Patent No. 3203977 JP-A 63-57707

  However, when applying the gas flow velocity measurement technique using the laser Doppler velocimeter of Patent Document 1 or the camera of Patent Document 2, dust attached to the coke and iron ore is scattered in the blast furnace. Therefore, in the case of an electromagnetic wave in a short wavelength region such as visible light or infrared light, the field of view is blocked and measurement cannot be performed while looking far away.

  In particular, the number of blast furnaces that have been newly renovated in recent years is increasing with a bellless type that does not have a top bell. This is intended to make it easier to achieve an appropriate charge distribution with the swivel chute, but because the swirl chute causes dust scattering, it is easy for the dust to float in the space above the stock line and obstructs the field of view. It has become.

  Moreover, in the method of calculating | requiring a gas flow rate based on the Doppler effect of the reflected wave by dust like the patent document 3 by transmitting a microwave, dust concentration is high and all dusts are obtaining the gas flow rate uniformly. In addition, since the reflected wave is scattered, it is difficult to distinguish an unnecessary signal (noise signal) from a signal that is effective as an original measurement target, resulting in variations in measurement results.

  This invention is made | formed in view of the above, Comprising: It aims at providing the gas flow rate measurement technique which measures the flow velocity of the gas in a blast furnace reliably and with high precision also in a blast furnace with high dust concentration.

  In order to solve the above-mentioned problems and achieve the object, the gas flow velocity measuring method according to the present invention is configured to generate an electromagnetic wave having a wavelength longer than that in the far-infrared region radiated from the raw material charged in the blast furnace. Included in the reception step of receiving at a position where the stacked shape of the raw material after charging is overlooked at the top, the spectrum analysis step of analyzing the spectrum of the received electromagnetic wave, the absorption spectrum detected by the spectrum analysis step, and the gas in the blast furnace And a gas flow rate calculating step for calculating a flow rate of the gas in the blast furnace based on a frequency difference from a known absorption spectrum of the substance to be obtained.

  Further, the gas flow velocity measuring method according to the present invention, in the above-described invention, includes a predetermined absorption spectrum including a known absorption spectrum of a substance contained in the gas in the blast furnace from a position where the stacked shape of the raw material after charging is seen at the top of the blast furnace The method includes a transmission step of transmitting an electromagnetic wave in a frequency band, wherein the reception step receives the electromagnetic wave in a predetermined frequency band transmitted in the transmission step.

  Further, the gas flow velocity measuring device according to the present invention is a receiving unit that receives electromagnetic waves having a wavelength longer than the far-infrared region provided at a position overlooking the stacked shape of the raw material after charging in the blast furnace, A blast furnace based on a frequency analysis unit for analyzing a spectrum of an electromagnetic wave received by the reception unit; and a frequency difference between an absorption spectrum detected by the spectrum analysis unit and a known absorption spectrum of a substance contained in a gas in the blast furnace. A gas flow rate calculation unit that calculates the flow rate of the internal gas.

  Moreover, the gas flow velocity measuring device according to the present invention includes a known absorption spectrum of the substance contained in the gas in the blast furnace, provided in the above-mentioned invention at a position where the stacked shape of the raw material after charging is overlooked at the top of the blast furnace. A transmission unit that transmits electromagnetic waves in a predetermined frequency band is provided, and the reception unit receives electromagnetic waves in a predetermined frequency band transmitted from the transmission unit.

  According to the present invention, in order to observe the absorption band of gas in the blast furnace by receiving electromagnetic waves spontaneously emitted from the inside of the blast furnace, receiving electromagnetic waves having a longer wavelength than microwaves and passing through dust, analyzing the spectrum, Compared to the conventional method for capturing the Doppler shift of the reflected wave due to dust by irradiating the gas, it is possible to reliably measure the gas flow rate with high accuracy without being affected by dust. Moreover, since the gas flow velocity can be directly observed rather than the indirect method of dust reflected waves, an effective signal can be obtained reliably and the measurement time resolution is good. Therefore, when the intensity of the electromagnetic wave emitted from the blast furnace is weak, an effective absorption spectrum can be reliably observed by transmitting an electromagnetic wave including the absorption band of the gas in the blast furnace, and highly accurate gas flow rate measurement is reliably performed. be able to.

FIG. 1 is a schematic diagram illustrating a configuration of a blast furnace including a gas flow velocity measuring device according to a first embodiment of the present invention. FIG. 2 is a flowchart showing a gas flow rate measurement processing procedure by the gas flow rate measuring apparatus shown in FIG. FIG. 3 is a diagram showing an absorption spectrum of CO gas that has undergone Doppler shift. FIG. 4 is a diagram showing a time-series change in the gas flow velocity displayed and output at the output unit. FIG. 5 is a diagram for explaining the frequency comb method. FIG. 6 is a diagram illustrating an installation example of the receiving antenna according to the first modification. FIG. 7 is a diagram illustrating an installation example of a receiving antenna according to the second modification. FIG. 8 is a schematic diagram showing a configuration of a blast furnace including a gas flow velocity measuring device according to the second embodiment of the present invention. FIG. 9 is a flowchart showing a gas flow rate measurement processing procedure by the gas flow rate measuring apparatus shown in FIG. FIG. 10 is a diagram illustrating an example of spectrum analysis by the spectrum analysis unit illustrated in FIG. 8.

  Embodiments of a gas flow velocity measuring method and a gas flow velocity measuring apparatus according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments.

[Embodiment 1]
FIG. 1 is a schematic diagram showing a configuration of a blast furnace 2 including a gas flow velocity measuring device 1 according to a first embodiment of the present invention. In FIG. 1, a blast furnace 2 forms a stock line 6 by charging and stacking a charge (raw material) 5 in a blast furnace furnace body 3 while rotating a turning chute 4 provided at the top of the furnace. Hot air blown from the tuyeres (not shown) in the lower part of the furnace inside the blast furnace body 3 blows up from the stock line 6 and is sucked by a dust collection duct 7 provided at the top of the furnace.

  The gas flow velocity measuring device 1 is a device that measures the flow velocity of the gas contained in the hot air in the blast furnace 2. The gas flow velocity measuring device 1 is provided in the blast furnace furnace body 3 and the apparatus main body 10 provided outside the blast furnace furnace body 3. And a receiving antenna 16. The receiving antenna 16 is connected to the connection portion 17 of the apparatus body 10 via a cable or a waveguide.

  The apparatus body 10 includes an input unit 11, an output unit 12, a spectrum analysis unit 13 that analyzes a spectrum of an electromagnetic wave having a wavelength longer than the far infrared region received by the receiving antenna 16, and an absorption detected by the analysis of the spectrum analysis unit 13. A gas flow rate calculation unit 14 for calculating the flow rate of the gas in the blast furnace based on the frequency difference between the spectrum and the known absorption spectrum, and a storage unit 15 are provided. These units are connected to the control unit C. The control unit C is realized by a CPU or the like, the input unit 11 is realized by a pointing device or the like, the output unit is realized by a liquid crystal display or the like, and the storage unit 15 is realized by a hard disk device or the like. In addition, the receiving antenna 16 is connected to the spectrum analysis unit 13 via the connection unit 17.

  The receiving antenna 16 is provided at the top of the blast furnace body 2 and is installed with the receiving direction directed vertically downward. Here, the hot air blown up from the stock line 6 is sucked by the dust collection duct 7 at the top of the furnace. For this reason, the flow velocity of the hot air containing the blast furnace gas has a vertical component in the vicinity of the stock line 6. Therefore, the receiving antenna 16 provided at the top of the furnace can capture the vertical component of the flow velocity of the hot air.

  Here, the gas flow rate measurement processing procedure by the control unit C will be described with reference to the flowchart shown in FIG. In FIG. 2, when the receiving antenna 16 receives an electromagnetic wave included in the blast furnace (step S <b> 101), the received signal is input to the spectrum analysis unit 13. The spectrum analysis unit 13 performs spectrum analysis for analyzing the intensity for each frequency component (step S102), and reads the frequency at which the intensity is minimized. Then, this minimum frequency f 'is detected as an absorption spectrum of the gas in the blast furnace (step S103).

  This detected absorption spectrum is caused by Doppler shift depending on the flow rate of the gas in the blast furnace. Accordingly, the gas flow rate calculation unit 14 obtains the frequency shift amount Δf based on the known absorption spectrum frequency f unique to the blast furnace gas and the Doppler shifted absorption spectrum frequency f ′ (step S104). The gas flow velocity v of the blast furnace gas is calculated (step S105), and the gas flow velocity v is sequentially stored in the storage unit 15.

  Thereafter, the output unit 12 performs a process of displaying and outputting the gas flow velocity v stored in the storage unit 15 by an appropriate display method (step S106).

The gas flow rate calculation unit 14 calculates the gas flow rate v based on the following equation (1). That is, since the frequency f of the absorption spectrum unique to the gas in the blast furnace is known in advance, the shift amount Δf of the frequency f ′ of the absorption spectrum observed for the gas in the blast furnace at the flow velocity v is expressed by the following equation (1). expressed.
Δf = f−f ′ = (v / c) f (1)
Where c is the speed of light.

(Application example)
Here, although there are various components in the blast furnace gas, the main gas composition is considered to be water vapor (H ₂ O), CO, and CO ₂ . In addition, H ₂ S, NO _X (X = 1, 2) and the like are included.

  In a gas such as CO, absorption due to rotational transition occurs, and an electromagnetic wave having a wavelength longer than that in the far infrared region is absorbed. For example, CO gas is known to have an absorption spectrum at 115 GHz. Therefore, in this application example, attention is focused on CO as the blast furnace gas.

  It is known that CO gas has a large number of absorption spectra in a frequency band of 100 GHz or more. FIG. 3 shows one of a plurality of observed absorption spectra. When attention is paid to the absorption spectrum near 115 GHz, it shifts to the high frequency side by Δf = 2 kHz from the known absorption spectrum of 115 GHz which is not Doppler shifted. From this, it is possible to calculate the gas flow velocity v = 5.2 (m / s) using the equation (1).

  Further, as shown in FIG. 4, for example, the output unit 12 can display and output a 24-hour time-series change in the gas flow rate.

  In the spectrum analyzer 13, since the shift amount Δf is very small with respect to the basic measurement frequency f ′, it is necessary to improve the frequency resolution. This can be realized by a method called a frequency comb method. it can.

In the frequency comb method, as shown in FIG. 5, a light source having a known frequency f ₀ is input to a frequency comb generator, and frequency combs (comb-like spectra arranged at equal intervals f _d in frequency space) are obtained. generate. Frequency unknown signal spectrum f _X interferes with close frequencies most of the frequency comb spectrum, the beat wave frequency f _b is generated. The beat wave is downscaled from the original signal, and can be rescaled to a frequency band that is easy to analyze.

Here, these frequencies have the relationship of the following formula (2).
_{f X = f b + f 0} + nf d ... (2)
However, n is a natural number.

According to this frequency comb method, a frequency resolution of about 10 ⁻¹² can be obtained. The downscaled signal can be input to a high-accuracy spectrum analyzer for spectrum analysis.

  In addition, the gas flow velocity calculated | required in this way represents the average value of the flow velocity of the gas which rises in the area | region with the surface which the stock line 6 forms. This region is determined by the directivity determined from the shape of the antenna.

  The receiving antenna 16 may be a horn antenna or a parabolic antenna optimized for a frequency band to be measured. In order to increase the directivity of the antenna and narrow the measurement range, a dielectric lens or the like may be used.

(Modification 1)
Moreover, as shown in FIG. 6, it is preferable to arrange a plurality of receiving antennas 16 in an annular shape on the inner periphery of the blast furnace body 3 and measure the gas flow velocity at a plurality of locations. This is because the entire gas flow velocity distribution can be measured based on the gas flow velocity at the plurality of locations. In FIG. 6, a plurality of receiving antennas 16 are provided along the inner periphery of the blast furnace body 3, but of course, it may be arranged in the center of the blast furnace body 3. In short, it is preferable to measure the entire surface of the stock line 6.

(Modification 2)
Alternatively, as shown in FIG. 7, the receiving antenna 16 may be rotated around a rotation shaft 16a inclined toward the center. Then, by periodically changing the direction (rotation angle) so as to overlook the entire interior of the blast furnace furnace body 3 and measuring the gas flow velocity, the entire gas flow velocity inside the blast furnace furnace body 3 can be obtained with one receiving antenna 16. Distribution can be measured. In this case, since the direction of the antenna has an angle with respect to the vertical direction, it is necessary to correct the measured gas flow rate to the gas flow rate component in the vertical direction.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. FIG. 8 is a schematic diagram showing the configuration of the blast furnace 2 including the gas flow velocity measuring device 1 according to the second embodiment of the present invention. In this Embodiment 2, it has the transmission part 18 which produces | generates the electromagnetic waves of the frequency of a specific band, and the antenna 19 for transmission which transmits the electromagnetic waves which the transmission part 18 produced | generated toward the stock line 6. FIG. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.

  The transmitter 18 continuously generates a sine wave in a band F1 ± ΔF1 centered on the frequency F1 of the absorption spectrum of the focused gas in the blast furnace. Similar to the receiving antenna 16, the transmitting antenna 19 is provided at the top of the furnace in the blast furnace body 3 so as to be directed downward in the vertical direction. The transmitting antenna 19 is connected to the apparatus main body 10 via the connection unit 171. Further, similarly to the receiving antenna 16, the transmitting antenna 19 is desirably a horn antenna or a parabolic antenna optimized for the frequency band to be used.

  The transmitting antenna 19 and the receiving antenna 16 may be realized as one antenna. In that case, it is necessary to provide a duplexer such as a directional coupler.

  In the second embodiment, it is possible to measure the gas flow rate with high accuracy even when the electromagnetic wave radiated from the focused gas in the blast furnace such as CO is weak. That is, since the absorption amount of the absorption spectrum depends on the concentration of the gas of interest, when the concentration of the gas of interest is low, the radiation spectrum may be weak as a whole. By transmitting electromagnetic waves in a band including the spectrum, the difference in intensity between the absorption spectrum of the gas in the blast furnace and the reflection spectrum in the other band can be increased, thereby facilitating discrimination of the absorption spectrum.

  Next, a gas flow rate measurement processing procedure according to the second embodiment will be described with reference to the flowchart shown in FIG. In FIG. 9, first, the transmitter 18 generates an electromagnetic wave having a frequency in a band (F1 ± ΔF1) where the absorption spectrum of the focused gas exists, and transmits the electromagnetic wave from the transmitting antenna 19 into the blast furnace (step S201). Here, ΔF1 is set to be sufficiently larger than the shift amount ΔF2 of the absorption spectrum of the focused gas. The receiving antenna 16 receives the electromagnetic wave in the blast furnace including the transmitted electromagnetic wave (step S202). Since a part of the transmitted electromagnetic wave is absorbed by the gas in the blast furnace, this absorption spectrum can be observed.

  The subsequent processing (steps S203 to S207) is the same as the processing (steps S102 to S106) shown in FIG. That is, when the received signal is input to the spectrum analysis unit 13, the spectrum analysis unit 13 performs spectrum analysis for analyzing the intensity of each frequency component (step S203), reads the frequency at which the intensity is minimized, Detection is performed as an absorption spectrum of the gas (step S204), and a shift amount ΔF2 is obtained based on the frequency F1 of the known absorption spectrum unique to the gas of interest and the frequency of the absorption spectrum observed after the Doppler shift ( Step S205), a process of calculating the gas flow velocity v is performed (Step S206), the gas flow velocity v is sequentially stored in the storage unit 15, and the output unit 12 displays the calculation result stored in the storage unit 15. This is performed (step S207).

  FIG. 10 is a diagram showing the results of spectrum analysis according to the second embodiment. At this time, absorption was observed at the position of F1 + ΔF2 (F1> ΔF2> 0). Since it is known that the focused gas absorbs the frequency of F1, the gas flow velocity v is obtained from the triangle F2 using the equation (1), and the data is sequentially recorded in the storage unit 15. The output unit 12 displays and outputs a 24-hour time-series change in the gas flow velocity v, as in FIG.

  In the second embodiment, as described above, the gas flow rate can be measured with high accuracy even when the electromagnetic wave radiated from the focused gas is weak.

By the way, for example, the absorption spectrum of CO is around 115 GHz, and when converted to a wavelength, it becomes about 2.5 mm. However, dust is scattered in the blast furnace body 3, and the wavelength of the spectrum and the size of the dust are large. In the case of the same level, the influence of scattering of electromagnetic waves by dust becomes large, and the measurement accuracy may be deteriorated. In this case, the measurement accuracy can be improved by focusing on NO ₂ (absorption spectrum is present in the vicinity of 53 GHz) or the like where the absorption spectrum is on the lower frequency side.

  In addition, a gas that does not cause a reaction in the blast furnace furnace body 3 and has an absorption spectrum in an appropriate frequency band is mixed in hot air blown from the tuyeres at the bottom of the furnace, and this gas is used as a gas in the blast furnace. Alternatively, the gas flow velocity may be obtained by observing the absorption spectrum.

  In the first and second embodiments described above, instead of obtaining the gas flow rate based on the Doppler shift amount for physically different sizes such as dust in the blast furnace body 3, the absorption spectrum of the blast furnace gas is Since the gas flow rate is directly obtained based on the Doppler shift amount, a highly accurate gas flow rate can be measured even in a blast furnace with a high dust concentration.

DESCRIPTION OF SYMBOLS 1 Gas flow velocity measuring apparatus 2 Blast furnace 3 Blast furnace furnace body 4 Swing chute 5 Charge 6 Stock line 7 Dust collection duct 10 Apparatus main body 11 Input part 12 Output part 13 Spectrum analysis part 14 Gas flow rate calculation part 15 Memory | storage part 16 Reception antenna 17,171 Connection unit 18 Transmitting unit 19 Transmitting antenna C Control unit

Claims (4)

A receiving step of receiving electromagnetic waves having a wavelength longer than the far-infrared region radiated from the raw material after charging in the blast furnace at a position where the stacked shape of the raw material after charging is overlooked at the top of the blast furnace;
A spectral analysis step of analyzing the spectrum of the received electromagnetic wave;
A gas flow rate calculating step for calculating the flow rate of the gas in the blast furnace based on the frequency difference between the absorption spectrum detected by the spectrum analysis step and the known absorption spectrum of the substance contained in the gas in the blast furnace;
A gas flow velocity measurement method comprising:   A transmission step of transmitting an electromagnetic wave of a predetermined frequency band including a known absorption spectrum of a substance contained in the gas in the blast furnace from a position where the stacked shape of the raw material after charging is overlooked at the top of the blast furnace furnace, and the reception step includes 2. The gas flow velocity measuring method according to claim 1, wherein the electromagnetic wave in the predetermined frequency band transmitted in the transmitting step is received. A receiver that receives electromagnetic waves having a wavelength longer than the far-infrared region at the top of the blast furnace, provided at a position overlooking the stacked shape of the raw materials after charging in the blast furnace,
A spectrum analyzer for analyzing a spectrum of the electromagnetic wave received by the receiver;
A gas flow rate calculation unit that calculates the flow rate of the gas in the blast furnace based on the frequency difference between the absorption spectrum detected by the spectrum analysis unit and the known absorption spectrum of the substance contained in the gas in the blast furnace;
A gas flow velocity measuring device comprising: Provided at a position where the stacked shape of the raw material after charging is overlooked at the top of the blast furnace, and includes a transmitter that transmits electromagnetic waves in a predetermined frequency band including a known absorption spectrum of a substance contained in the gas in the blast furnace,
The gas flow rate measuring device according to claim 3, wherein the receiving unit receives an electromagnetic wave having a predetermined frequency band transmitted from the transmitting unit.

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